It is well known that hair is composed of a unique protein material called "keratin", which is distinguished by the fact that it contains a very significant amount of an amino acid (cystine) which contains the element sulfur in addition to the elements nitrogen, oxygen, carbon and hydrogen. In the natural synthesis of hair, the element sulfur covalently links intra or inter polypeptide chains (K) through two sulfur atoms (S--S) to give keratin protein (K--S--S--K). Only by chemical action can this covalent linkage be broken.
In this regard, many prior art compositions have been developed for the "cold permanent waving" of hair. Typically, these prior art systems treat the hair with a reducing agent which breaks the disulfide (cystine) linkage in the hair while the hair is wound around a curling rod.
In general, permanent hair waving is usually carried out by subjecting the hair to reagents containing a free--SH group or thiol. These materials are also called mercaptans. In this treatment, the hair usually is either wrapped on the rods with water or the lotion containing the thiol, and then saturated with thiol lotion. The thiol waving agent acts to break the disulfide bonds within the hair fiber forming thiol groups in the hair protein and disulfide bonds between two thiol waving agent molecules. The chemistry involved in the reaction of the mercaptan with the cystine disulfide bonds in the hair fiber is illustrated by the following chemical equations: EQU KSSK+2KSH.div.2KSH+RSSR EQU KSSK+2RSH.div.KSR+KSH
When a sufficient number of hair disulfide bonds have been broken, the hair is realigned to pair previously unpaired hair protein thiol groups opposite each other. At this point, the hair is rinsed, removing the unreacted thiol waving agent and disulfide reaction product formed from it. Then, the hair is saturated with an oxidizing agent, or neutralizer, such as hydrogen peroxide or bromate salt, to reform disulfide bonds between the newly paired hair protein thiols, thereby giving the hair a new configuration or wave, or adding curl to the hair. By rebonding the sites of the reduced keratin in their new curled configuration, a permanent set which is impervious to water is established.
Much of the rebonding of the reduced sites is accomplished by the action of the chemical oxidizing agent, which is typically hydrogen peroxide and can be illustrated by the following chemical reaction: EQU 2 KSH+H.sub.2 O.sub.2 .fwdarw.KSSK+2H.sub.2 O.
In the art of permanent waving, there is much trial and error, with the hair being over-processed, in some instances. The characteristics of over-processing are raspy feel to the hair or a bleaching of the natural underlying color. Structural evaluation of the hair fiber by instrumentation usually reveals that the structural integrity of the hair is lessened, which is evidenced by either an increase in the amount of cysteine and cystic acid or a lessening of the cystine content relative to the hair not so processed.
Some detrimental effect to hair fiber is unavoidable, as the process of permanent waving involves controlled bond scission of the disulfide linkages within the keratin proteins. Recovery of these disulfides is the determining factor for the tightness of the curls and overall tensile strength.
For these reasons, improved oxidizing agents or neutralizers which might be more efficient in reforming the disulfide bonds is constantly being sought. The typical oxidizing agents used in the art of hair care are hydrogen peroxide and the alkali metal and ammoniated salts of bromate, persulfate and carbonates. However, these conventional oxidizing agents typically exhibit such disadvantages as the bleaching of the hair, skin irritation and instability in solution.
In an attempt to eliminate these prior art difficulties and drawbacks typically encountered with the oxidizing or neutralizing agents, attention has been paid to chlorite, chlorite salts, and aqueous solutions of chlorite.
First, these aqueous solutions tend to decompose to the other equilibrium species of hypochlorous acid that is, hypochlorite and chlorine dioxide. Both of these chemicals damage the cuticle and other components of hair with the net result that the hair takes on the appearance of being "damaged", e.g., there may be a raspy feel to the hair and even some degree of lightening. Second, and of more serious concern, is that both hypochlorite and chlorine dioxide can irritate skin more so than either hydrogen peroxide, persulfate, or bromate.
U.S. Pat. No. 3,265,582 teaches that salts: of chlorate and perchlorate are capable of oxidizing hair which had been previously relaxed and so imparting a wave to the hair. The solutions so described are aqueous. German Patent No. 2,039,358 describes the use of chlorates to affect the color formation of standard oxidation dyes to color the hair and by doing so establishes that variants of hypochlorous acid in the lower oxidation states are indeed applicable to the art of hair care. More recently, U.S. Pat. No. 4,776,857 introduced the use of perhalosalts, perchlorates included, to affect the in-situ condensation of indole derivatives also for the exclusive effect of coloring the hair. Unfortunately, there is the severe drawback to use of such oxychlorine salts in that they are typically unstable in water and must therefore be mixed immediately prior to use and more so, the solutions are irritating to skin.
In U.S. Pat. No. 2,899,965, the use of specifically aqueous chlorite, preferably, derived from sodium chlorite as the oxidizing agent in a permanent wave solution, is discussed. However, in addition to describing the advantages of chlorite, the undesirable features associated with chlorite compositions are also fully discussed. In particular, the chlorite solutions were used by working through the hair after unwinding from the roller followed by rewrapping. Chlorite compositions can explode into flames or cause organic materials to spontaneously combust when brought in contact with reductants such as thioglycolic acid, especially if the combinations were allowed to dry. In an attempt to overcome these extremely detrimental properties, which rendered such chlorite inapplicable for commercial use, additives such as urea and sodium lactate were disclosed.
It has been demonstrated that aqueous solutions of chlorite can convert mercaptans into disulfides, and hence, in the process of permanent waving, thereby neutralize a permanent wave solution to impart a wave to hair [see, for example, T. Ruemele in Kosmetic; Vol. #23; pp. 695-696; (1957); and K. Plouch and D. Dziewonska: Roc. Chemi Ann. Soc. Chim.; Vol. 41; pp. 1285-1289; (1967)]. In Kosmetic, the use of aqueous sodium chlorite is discussed for permanent waving. In that discussion, the concentration of chlorite, which was generated in-situ, is estimated at 4% to 10%. However, these earlier experiments suggested that there were several problems associated with the use of this material in purely aqueous media.
In U.S. Pat. No. 2,780,579, the use of chlorite in association with ascorbic acid to produce dehydroasorbic acid using sodium chlorite as well as other conventional oxidizing compounds is provided.
Although substantial effort has been expended in developing commercially employable oxidizing mixtures or neutralizers, it is clearly apparent that prior art systems have failed to develop a chlorite based oxidizing mixture which is easy to produce, store and use. Typically, the prior art problems detailed in the patents identified above have continued and have been incapable of being eliminated, prior to the present invention.
Therefore, it is a principal object of the present invention to provide a chlorite based solution which attains the advantages well known for chlorite solutions, without experiencing any of the difficulties and drawbacks previously encountered with chlorite solutions.
Another object of the present invention is to provide a chlorite based solution having the characteristic features described above which can be formulated inexpensively and used widely without any detrimental effects.
Another object of the present invention is to provide a chlorite based solution having the characteristic features described above which can be employed as a neutralizer or an oxidizer in the permanent waving of hair.
Another object of the present invention is to provide a chlorite based solution having the characteristic features described above which can be used as an additive to commercially available oxidizers or neutralizers.
A further object of the present invention is to provide a chlorite based solution having the characteristic features described above which can be employed as a post treatment for permanently waved hair.
Other and more specific objects will in part be obvious and will in part appear hereinafter.